Magnetic bearing device and centrifugal pump

Abstract

A magnetic bearing device is proposed for the contactless magnetic bearing of a rotor (3) comprising a disk-shaped or annular magnetically active core (31), wherein the magnetic bearing device has a stator (2) comprising a plurality of coil cores (25), each of which comprises a longitudinal leg (26) extending from a first end (261) in an axial direction (A) to a second end (262), and a transverse leg (27) arranged at the second end (262) of the longitudinal leg and extending in a radial direction perpendicular to the axial direction (A), wherein at least one concentrated winding (61) is provided on each longitudinal leg (26), which surrounds the respective longitudinal leg (26), wherein the stator (2) further has a cup-shaped recess (211) into which the rotor (3) can be inserted,wherein the cup-shaped recess (211) is arranged at an axial end of the stator (2), wherein the transverse legs (27) are arranged around the cup-shaped recess (211), and wherein a plurality of magnetic field sensors (8) for determining the position of the rotor (3) are arranged around the cup-shaped recess (211). An annular holding device (9) is provided for the magnetic field sensors (8), which has a cavity (95) for each magnetic field sensor (8), which is delimited with respect to the radial direction by an inner wall (951) and by an outer wall (952), wherein the magnetic field sensor (8) can be inserted into the cavity (95), and wherein the cavity (95) is dimensioned such that the inner wall (951) and the outer wall (952) lie flat against the magnetic field sensor (8). Furthermore, a centrifugal pump with such a magnetic bearing device is proposed.

Description

[0001] The invention relates to a magnetic bearing device according to the preamble of the independent patent claim and a centrifugal pump with such a magnetic bearing device.

[0002] Magnetic bearing devices for contactless magnetic bearings of a rotor have the advantage that they do not require mechanical bearings for the rotor. The rotor is supported or stabilized by magnetic forces generated by a stator of the magnetic bearing device. Due to the absence of mechanical bearings, such magnetic bearing devices are particularly suitable for pumping, mixing, centrifuging, or stirring devices that convey very sensitive substances, such as blood pumps, or that have very high purity requirements, for example in the pharmaceutical or biotechnology industries, or that convey abrasive or aggressive substances that would quickly destroy mechanical bearings, such as pumps or mixers for slurry, sulfuric acid, phosphoric acid, or other chemicals in the semiconductor industry.

[0003] In the biotechnology industry, such magnetic bearing devices are used, for example, in connection with bioreactors, e.g., in centrifugal pumps for conveying fluids into or out of the bioreactor, or in mixing devices that mix the fluids in the bioreactor. In the semiconductor industry, such magnetic bearing devices are used not only for conveying aggressive or abrasive substances, but also, for example, in rotating devices used to rotate wafers.

[0004] It is also known to use magnetic bearing devices for viscometers.

[0005] An advantageous and known embodiment of a magnetic bearing device is the temple-type design, to which the present invention also relates.

[0006] The characteristic of the temple design is that the stator of the magnetic bearing device has a plurality of coil cores, each of which comprises a longitudinal leg extending from a first end in an axial direction to a second end. The axial direction refers to the direction defined by the nominal axis of rotation of the rotor, which is mounted with the magnetic bearing device. The nominal axis of rotation is the axis of rotation about which the rotor rotates in the operating state when it is in a centered and untilted position with respect to the stator. In addition to the longitudinal leg, each coil core comprises a transverse leg, which is arranged at the second end of the longitudinal leg and which extends in the radial direction - usually inwards - wherein the radial direction is perpendicular to the axial direction. The transverse leg therefore extends essentially at right angles to the longitudinal leg.The coil cores are each shaped like an L, with the cross legs forming the short legs of the L. The rotor to be mounted is then arranged between the cross legs.

[0007] The majority of the longitudinal legs, which extend in an axial direction and are reminiscent of the columns of a temple, gave this type of construction its name.

[0008] In one embodiment, the stator of the magnetic bearing device has, for example, six coil cores arranged in a circle and equidistant around a cup-shaped recess into which the rotor can be inserted. The first ends of the longitudinal legs are usually connected circumferentially by a return wire, which serves to guide the magnetic flux. The rotor to be mounted comprises a magnetically active core, for example a permanent-magnetic disk or a permanent-magnetic ring, which is arranged between the radially inner ends of the transverse legs and rotates about the axial direction in the operating state, wherein the rotor is magnetically mounted with respect to the stator in a contactless manner.

[0009] For such magnetic bearing devices, it is not necessary for the magnetically active core of the rotor to be permanently magnetic. Designs are also known in which the magnetically active core of the rotor is designed without permanent magnets. The magnetically active core of the rotor is then, for example, ferromagnetic and consists of iron, nickel-iron, cobalt-iron, silicon-iron, mu-metal, or another ferromagnetic material.

[0010] Furthermore, designs are possible in which the magnetically active core of the rotor comprises both ferromagnetic and permanent magnetic materials. For example, permanent magnets can be inserted or embedded into a ferromagnetic base body. Such designs are advantageous, for example, when reducing costs for large rotors by saving on permanent magnetic material.

[0011] To generate the electromagnetic fields necessary for the contactless magnetic bearing of the rotor, the longitudinal limbs carry windings. The windings are designed, for example, so that a concentrated winding is wound around each longitudinal limb, meaning that the coil axis of each concentrated winding extends in the axial direction. It is typical for the temple design that the coil axes of the concentrated windings run in the axial direction and that the concentrated windings are not arranged in the radial plane in which the rotor or the magnetically active core of the rotor is mounted in operation.

[0012] Configurations are possible in which exactly one concentrated winding is arranged on each longitudinal leg. In other configurations, several, for example, exactly two, concentrated windings are provided on each longitudinal leg. Configurations are also possible in which windings are wound around two circumferentially adjacent longitudinal legs, so that these two adjacent longitudinal legs are both located in the interior of the concentrated winding.

[0013] For reliable and safe contactless magnetic bearing of the rotor, it is very important to know the current position of the rotor in the radial plane with a high degree of accuracy so that the position of the rotor in the radial plane can be controlled to a desired position. To determine the position of the rotor, it is known, for example from WO 2014 / 036419, to arrange a plurality of magnetic field sensors, for example Hall sensors, in the magnetic bearing device so that they are arranged around the magnetically active core of the rotor. The current position of the rotor is then determined as accurately as possible from the signals of the magnetic field sensors. However, since the magnetic field sensors detect all magnetic fields at their respective positions, including, for example, the stator magnetic field, it is often very difficult to determine the exact position of the rotor in the radial plane from the signals of the magnetic field sensors.

[0014] Based on this prior art, it is therefore an object of the invention to propose a magnetic bearing device for the contactless magnetic bearing of a rotor with a ring- or disk-shaped magnetically active core, in which the position of the rotor can be determined reliably and with very high accuracy using magnetic field sensors. Furthermore, it is an object of the invention to propose a centrifugal pump with such a magnetic bearing device.

[0015] The subject matter of the invention solving this problem is characterized by the features of the independent patent claim.

[0016] According to the invention, a magnetic bearing device is proposed for the contactless magnetic bearing of a rotor comprising a disk-shaped or annular magnetically active core, wherein the magnetic bearing device has a stator which comprises a plurality of coil cores, each of which comprises a longitudinal leg extending from a first end in an axial direction to a second end, and a transverse leg which is arranged at the second end of the longitudinal leg and extends in a radial direction which is perpendicular to the axial direction, wherein at least one concentrated winding is provided on each longitudinal leg, which surrounds the respective longitudinal leg, wherein the stator further has a cup-shaped recess into which the rotor can be inserted, wherein the cup-shaped recess is arranged at an axial end of the stator,wherein the transverse legs are arranged around the cup-shaped recess, and wherein a plurality of magnetic field sensors for determining the position of the rotor are arranged around the cup-shaped recess. An annular holding device is provided for the magnetic field sensors, which has a cavity for each magnetic field sensor, which is bounded in the radial direction by an inner wall and an outer wall. The magnetic field sensor can be inserted into the cavity, and the cavity is dimensioned such that the inner wall and the outer wall lie flat against the magnetic field sensor.

[0017] By providing an annular holder with a cavity for each magnetic field sensor, the cavity is dimensioned such that the inner and outer walls lie flat against the magnetic field sensor. The respective position of the magnetic field sensor is known with extremely high accuracy. In particular, the position of the magnetic field sensors relative to the cup-shaped recess is known with high accuracy, which enables a very precise determination of the position of the rotor in the cup-shaped recess. In particular, the position of each magnetic field sensor is defined only by the location of the cavity and does not depend on how, for example, the magnetic field sensor is soldered to a circuit board or glued to a structure.If the position of a magnetic field sensor is determined by connections such as soldering or gluing, this generally results in inaccurate positioning, which negatively impacts the accuracy of the rotor position determination. Since soldering or gluing connections cannot influence the position of the magnetic field sensor in the inventive design, a very high degree of accuracy in determining the rotor position results.

[0018] According to a preferred embodiment, a circuit board on which all magnetic field sensors are arranged is arranged between the windings and the transverse limbs with respect to the axial direction, and the holding device is designed to accommodate the circuit board. This has the advantage that all magnetic field sensors can first be connected to the circuit board, with the electrical connections for controlling the magnetic field sensors and for receiving the measurement signals being established on the circuit board. The circuit board, with the magnetic field sensors connected to it, is then inserted into the holding device, with the magnetic field sensors being pushed into the cavities. Finally, the circuit board is firmly connected to the holding device, for example by means of screws and / or by means of a potting compound with which the holding device is cast.

[0019] It is preferred that the holding device has an annular edge with a shoulder provided thereon, wherein the shoulder is arranged radially inwardly of the edge, and wherein the circuit board rests against the shoulder. This shoulder thus forms a support for the circuit board, allowing it to be placed in the holding device very easily.

[0020] Furthermore, it is preferred that the edge be configured such that it projects beyond the circuit board in the axial direction. This measure makes it possible to encapsulate the holding device with a potting compound, with the circuit board being completely covered by the potting compound.

[0021] According to a preferred embodiment, the holding device has a separate recess for each coil core, which encloses the coil core and receives the transverse leg of the coil core.

[0022] It is advantageous that each cavity is arranged between two adjacent recesses in the circumferential direction. This makes it possible for each magnetic field sensor to be arranged between two adjacent coil cores in the circumferential direction.

[0023] According to a particularly preferred embodiment, exactly six coil cores are provided in the magnetic bearing device.

[0024] Furthermore, it is preferred that the magnetic bearing device comprises exactly six magnetic field sensors, which are preferably arranged equidistantly around the cup-shaped recess.

[0025] In a preferred embodiment, the holding device is filled with a first potting compound such that the circuit board is completely covered by the potting compound. The first potting compound is particularly preferably a soft potting compound. In the context of this application, a soft potting compound means a potting compound with a Shore D hardness of less than 40. A silicone or polyurethane, for example, is suitable as the first potting compound.

[0026] According to a particularly preferred embodiment, the coil cores with the windings arranged thereon are arranged in a housing which is cast with a second casting compound, wherein the second casting compound is a thermally conductive casting compound. This second, thermally conductive casting compound is a hard thermal casting compound, for example an epoxy resin. Consequently, the first casting compound and the second, thermal casting compound are different from one another. During operation of the magnetic bearing device, significant and frequent temperature fluctuations can occur, particularly in the region of the holding device with the magnetic field sensors arranged therein. A soft casting compound is more resistant to such fluctuations. Therefore, a soft casting compound is preferred for casting the holding device, which is softer than the hard casting compound with which the housing is cast.The second potting compound, which in particular encloses the coil cores and the windings arranged thereon, preferably has particularly good thermal conductivity in order to dissipate the generated heat, e.g., the heat generated by copper and iron losses, as efficiently as possible. To achieve high thermal conductivity, thermally highly conductive fillers, such as graphite powder, carbon fibers, carbon nanotubes, aluminum oxide powder, boron nitride powder, or other ceramic powders, are preferably added to the second thermal potting compound. These fillers improve thermal conductivity but also increase the hardness of the cured potting compound. Therefore, the second thermal potting compound has a greater hardness, in particular a higher Shore D hardness, than the first potting compound.

[0027] With a view to achieving the most precise positioning of the magnetic field sensors, it is advantageous to provide a separate guide element for each cavity, which forms the inner wall or the outer wall by which the cavity is delimited. Such separate guide elements can usually be manufactured more easily and with very high precision than the entire holding device, which is manufactured, for example, using an injection molding process. To form the cavity for the magnetic field sensor, the separate guide element is inserted in the axial direction into a recess provided for this purpose in the holding device, so that it subsequently forms the inner wall or the outer wall, which delimit the cavity in the radial direction. The separate guide element is preferably connected to the holding device in a form-fitting manner, for example by means of a press fit.

[0028] The stator preferably has a containment shell which forms one axial end of the stator, wherein the containment shell has the cup-shaped recess into which the rotor can be inserted, and wherein the containment shell encloses the holding device radially on the outside. In this preferred embodiment, the containment shell is preferably designed as a separate containment shell which has the cup-shaped recess. In particular for design reasons, it is preferred that the containment shell encloses the second holding device radially on the outside. In this case, an axial end region of the second holding device is arranged within the containment shell and is completely enclosed by it in the circumferential direction.

[0029] Preferably, the holding device is made of a plastic. For example, the holding device is designed as an injection-molded part that is manufactured using an injection molding process.

[0030] Furthermore, it is preferred that the containment shell be made of a plastic material. The containment shell can also be designed as an injection-molded part.

[0031] According to a preferred embodiment, the magnetic bearing device has a housing which comprises a stator housing and a control housing which are arranged adjacent to one another with respect to the axial direction, wherein the stator housing is designed to accommodate the coil cores with the concentrated windings arranged thereon, and the control housing is designed to accommodate a control unit for controlling and supplying the windings with electrical energy for generating electromagnetic fields.

[0032] The housing is preferably designed such that the coil cores with the concentrated windings arranged thereon can be inserted into the stator housing in a first installation direction in the axial direction, and the control unit can be inserted into the control housing in a second installation direction, wherein the first installation direction is opposite to the second installation direction. The housing preferably has two separate areas, one of which forms the stator housing and the other the control housing. These two areas can be separated from each other, for example, by a wall which has passages, e.g. for electrical connections. The housing is then preferably designed as a single piece with respect to the circumferential direction.

[0033] According to a particularly preferred embodiment, the stator of the magnetic bearing device is designed to generate a torque with which the rotor can be magnetically driven in a contactless manner for rotation about the axial direction.

[0034] The invention further proposes a centrifugal pump for conveying a fluid, which comprises a magnetic bearing device according to the invention, and a rotor with a magnetically active core, wherein the rotor can be inserted into the cup-shaped recess of the containment shell, and wherein the rotor is designed as a rotor of the centrifugal pump.

[0035] Further advantageous measures and embodiments of the invention emerge from the dependent claims.

[0036] The invention is explained in more detail below using exemplary embodiments and the drawings. The drawings show: Fig. 1: a sectional view of an embodiment of a magnetic bearing device according to the invention, Fig. 2: a perspective view of the embodiment of Fig. 1 in a perspective exploded view, Fig. 3 a perspective view of the stator and the holding device, Fig. 4: a perspective exploded view of the coil cores, the windings and the holding device, Fig. 5: a perspective view of the holding device from the direction of the first ends of the longitudinal legs of the coil cores, Fig. 6: as Fig. 5 , but from the opposite view, Fig. 7: a perspective exploded view of the holding device and the circuit board with the magnetic field sensors, Fig. 8: a sectional view of the holding device with the circuit board inserted therein, Fig. 9: the detail I from Fig. 8 in an enlarged view, Fig. 10: a perspective view of the guide element from Fig. 9 , Fig. 11: a sectional view of the containment shell of the stator, and Fig. 12: a schematic sectional view of an embodiment of a centrifugal pump according to the invention in a section in the axial direction.

[0037] Fig. 1 shows a sectional view of an embodiment of a magnetic bearing device according to the invention, which is designated overall by the reference numeral 1. The magnetic bearing device 1 is designed for the contactless magnetic bearing of a rotor 3, which comprises a disk-shaped or annular magnetically active core 31.

[0038] For a better understanding, Fig. 2 another perspective view of the embodiment from Fig. 1 in a perspective exploded view, where Fig. 2 the rotor 3 is not shown. The magnetic bearing device 1 is designed according to the temple design and comprises a stator 2, which has a plurality of coil cores 25 - here six coil cores 25 - each of which comprises a longitudinal leg 26 which extends from a first end 261 in an axial direction A to a second end 262, and a transverse leg 27 arranged perpendicular to the longitudinal leg 26 and extends in a radial direction that is perpendicular to the axial direction A. Each transverse leg 27 is delimited with respect to the radial direction by an end face 271 which forms the pole of the associated coil core 25.

[0039] On each longitudinal leg 25, at least one, in this embodiment exactly one, concentrated winding 61 is provided, which encloses the respective longitudinal leg 26.

[0040] The magnetic bearing device 1 comprises a housing 10 in which the coil cores 25 are arranged.

[0041] For a better understanding, the Fig. 3 und Fig. 4 further representations of the stator 2 of the embodiment of the magnetic bearing device 1, wherein the housing 10 is not shown. Fig. 3 shows a perspective view of the stator 2 and a holding device 9, which will be described in more detail. Furthermore, Fig. 3 a return 22 is provided, which connects all first ends 261 of the longitudinal legs 26 - that is, the ones shown ( Fig. 1 ) lower ends 261 - and serves to guide the magnetic flux. The return path 22 is preferably annular. Fig. 4 shows a perspective exploded view of the coil cores 25 with the concentrated windings 61 arranged thereon and the holding device 9.

[0042] The housing 10 is preferably made of a metallic material, such as aluminum or stainless steel. For improved chemical resistance, the housing 10 can be provided with a coating, preferably a plastic coating made of a highly chemically resistant plastic. Examples of such plastics are PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy polymers), ECTFE (ethylene chlorotrifluoroethylene), ETFE (ethylene tetrafluoroethylene), epoxy resin (polyepoxide), PPA (polyphthalamide), and PE (polyethylene). Depending on the intended application, the housing 10 can also be made of titanium or chromium steel.

[0043] The stator 2 further comprises a containment shell 21 with a cup-shaped recess 211 (see also Fig. 11 ), into which the rotor 3 to be supported can be inserted (see Fig. 1 ). The containment shell 21 forms one of the two axial ends of the stator 2 or the magnetic bearing device 1, as shown in Fig. 1 the upper axial end of the stator 2. At the other axial end of the magnetic bearing device 1, a housing cover 11 is arranged, which closes the housing 10.

[0044] The containment shell 21 is firmly connected to the housing 10, for example by means of a positive connection and / or by means of an elastic seal 201. Preferably, the containment shell 21 is hermetically sealed to the housing 10. The housing cover 11 is firmly connected to the housing 10, for example by means of screws 111 ( Fig. 1 ), wherein a sealing element 105 is optionally arranged between the housing cover 11 and the housing 10. The sealing element 105 can in particular be designed as a flat gasket. Preferably, the housing cover 11 is hermetically sealed to the housing 10.

[0045] Particularly preferably, the housing 10, together with the containment shell 21 and the housing cover 11, forms a hermetically sealed housing in which the other components of the stator 2 are hermetically encapsulated. The housing 10 is preferably filled with a thermally highly conductive potting compound, for example, an epoxy resin, so that the components arranged inside the housing 10 are surrounded by the potting compound. This reduces the overall thermal resistance and dampens vibrations.

[0046] The housing cover 11 is preferably made of a plastic. A chemically resistant plastic such as polypropylene is particularly preferred for applications in chemically aggressive environments.

[0047] The transverse legs 27 of the coil cores 25 are arranged in the containment shell 21 in such a way that the end faces 271 of the transverse legs 27 are arranged around the cup-shaped recess 211.

[0048] The coil cores 25 of the stator 2 are arranged equidistantly on a circular line, so that the end faces 271 surround the magnetically active core 31 of the rotor 3 when the rotor 3 is inserted into the cup-shaped recess 211. On each longitudinal leg 26, exactly one concentrated winding 61 is provided, which surrounds the longitudinal leg 26.

[0049] In other embodiments, more than one concentrated winding can be arranged on the longitudinal legs 26. For example, there are embodiments in which exactly two concentrated windings are provided on each of the longitudinal legs 26, each of which surrounds the respective longitudinal leg 26, wherein the two windings arranged on the same longitudinal leg 26 are arranged adjacent to one another with respect to the axial direction A.

[0050] The concentrated windings 61 serve to generate electromagnetic fields with which the rotor 3 can be magnetically supported in a contactless manner in the cup-shaped recess 211 of the containment shell 21.

[0051] Furthermore, a control unit 40 is provided for controlling and supplying the windings 61 with electrical energy. The control unit 40 comprises, in particular, the power electronics, for example, the converters or rectifiers, which feed the required currents into the windings 61. The control unit 40 is Fig. 1 and in Fig. 2 Particularly preferably, the control unit 40 is also arranged within the housing 10, for example as shown ( Fig. 1 ) below the first ends 261 of the longitudinal legs 26 of the coil cores 25. The control unit 40 is preferably also encapsulated with a thermal casting compound or coupled to the housing 10 and the return path 22 and / or the coil cores 25 of the stator 2. The control unit 40 preferably comprises an electronics board 41 on which various electronic components 42 are arranged.

[0052] As is particularly the case in the Fig. 1 and Fig. 2 As can be seen, the housing 10 preferably comprises two separate areas arranged adjacent to one another with respect to the axial direction A, one of which forms a stator housing 101 and the other a control housing 102. The stator housing 101 of the housing 10 is designed to receive the coil cores 25 with the windings 61 arranged thereon, and the control housing 102 is designed to receive the control unit 40.

[0053] According to a preferred measure, the housing 10 comprises an inner cup 13, which is essentially cylindrical and is arranged radially inward with respect to the windings 61 in the interior space surrounded by the windings 61. The inner cup 13 is connected to an outer wall 15 of the housing 10 via a flange-like projection 14. The outer wall 15 forms the radially outer boundary of the housing 10. Particularly preferably, the inner cup 13 and the flange-like projection 14 are integral components of the housing 10. The outer wall 15, the flange-like projection 14, and the inner cup 13 are configured as a single piece and form the preferably single-piece housing 10.

[0054] The inner cup 13 and the flange-like projection 14 separate the area of ​​the housing 10 which forms the stator housing 101 from the area which forms the control housing 102.

[0055] The inner cup 13 connected to the flange-like projection 14 extends from the radially inner edge of the flange-like projection 14 in the axial direction A and is arranged radially inward with respect to the windings 61 and the return path 22 in the interior space surrounded by the windings 61, as can be seen in particular in Fig. 1 can be seen. With respect to the radial direction, the inner cup 13 is arranged adjacent to the longitudinal legs 26 of the coil cores 25 and the windings 61 arranged thereon, so that the inner cup 13 can absorb and dissipate the heat generated by the windings 61 and the coil cores 25 particularly well. With respect to the axial direction A, the inner cup 13 extends approximately to the cup-shaped recess 211 of the can 21.

[0056] As this is particularly the case in Fig. 2 As can be seen, the stator housing 101 of the housing 10 is designed with an interior space which has a substantially circular or annular cross-sectional area perpendicular to the axial direction A. This is preferred because the stator housing 101 can thereby particularly well accommodate the annular short circuit 22 with the coil cores 25 arranged around the short circuit 22. The control housing 102 of the housing 10 is designed with an interior space which has a substantially rectangular or square cross-sectional area perpendicular to the axial direction A. This is preferred because the control housing 102 is thereby particularly well suited to accommodate the preferably rectangular or square electronics board 41 of the control device 40. A rectangular or square design of the electronics board 41 is, in particular with regard to production, considerably simpler than, for example, a round design.

[0057] Due to this configuration of the stator housing 101 and the control housing 102, the axial end of the stator 2, at which the containment shell 21 closes the housing 10, has a substantially round cross-section, so that the containment shell 21 has a round or annular configuration. In contrast, the axial end of the stator 2, at which the housing cover 11 closes the housing 10, has a substantially rectangular or square cross-section, so that the housing cover 11 has a rectangular or square configuration.

[0058] With exemplary character are in Fig. 1 some components of the control unit 40 are shown. The control unit 40 comprises, for example, the electronics board 41, on which the electronic components 42 are provided, e.g., the power electronics for controlling the windings 61. The electronics board 41 can also contain, for example, evaluation electronics for evaluating the signals from sensors, e.g., magnetic field sensors, and serve as a communication interface. The electronics board 41 is preferably designed as an electronic print or PCB (printed circuit board). Furthermore, a connecting cable 45 is provided, which is connected to the electronics board 41 via a cable connection (not shown) or a plug. The connecting cable 45 leads out of the housing 10 and serves, for example, to supply power to the magnetic bearing device 1. The connecting cable 45 is led out of the housing 20 by means of a sealingly designed cable feedthrough 47.Preferably, the cable feedthrough 47 is designed to be hermetically sealed.

[0059] The electronics board 41 of the control device 40 is connected to the windings 61 via connecting lines (not shown), for example, cables, in order to control and supply them with energy. It is understood that feedthroughs or openings through which the connecting lines are routed are provided between the control housing 102 and the stator housing 101. Such feedthroughs can be arranged, for example, in the flange-like projection 14 or in the inner cup 13.

[0060] The electronics board 41 is preferably arranged directly on the flange-like projection 14, so that the electronics board rests against the flange-like projection 14. This makes it possible to dissipate the heat generated in the control unit 40 via the housing 10 in a particularly efficient manner. Preferably, the main heat sources in the control unit 40, for example, the power switches for the windings 61, are arranged in the areas of the electronics board 41 that rest against the flange-like projection 14.

[0061] The interior of the inner cup 13, i.e. the space enclosed by the inner cup 13, can be used for additional electronic components, electronic boards or connectors or connections. These are Fig. 1 not shown for reasons of clarity.

[0062] According to a particularly preferred embodiment, the stator 2 is designed such that, in addition to the contactless magnetic bearing of the rotor 3, it can also exert a torque on the rotor 3 or the magnetically active core 31 of the rotor 3, which drives the rotor 3 to rotate about a desired axis of rotation. The desired axis of rotation refers to the axis about which the rotor 3 rotates in the operating state when the rotor 3 is in a centered and non-tilted position with respect to the stator 2, as shown in Fig. 1 This desired axis of rotation extends in the axial direction A, i.e., in this preferred embodiment, the rotor 3 arranged in the containment shell 21 of the stator 2 can be driven to rotate about the axial direction A. Typically, the desired axis of rotation coincides with the central axis of the stator 2, which extends in the axial direction A.

[0063] In this embodiment, the concentrated windings 61 thus generate electromagnetic rotating fields with which the rotor 3 can be supported magnetically with respect to the stator 2 without contact and can also be driven to rotate about the axial direction A without contact.

[0064] It is understood that the number of six coil cores 25 is preferred, but should be understood only as an example. Of course, embodiments are also possible in which the stator 2 has fewer than six, e.g., five or four or three coil cores 25, or in which the stator 2 has more than six, e.g., seven or eight or nine coil cores 25, or any larger number of coil cores 25.

[0065] The rotor 3 comprises the magnetically active core 31, which is ring-shaped or disc-shaped. The magnetically active core 31 is, as shown in Fig. 1 designed as a ring and defines a magnetic center plane. Alternatively, the magnetically active core 31 can also be designed as a disk. As a rule, in the case of a disk-shaped or ring-shaped magnetically active core 31, the magnetic center plane is the geometric center plane of the magnetically active core 31 of the rotor 3, which is perpendicular to the axial direction A. In the operating state, the magnetically active core 31 is mounted in a radial plane E, which is perpendicular to the axial direction A. The radial plane is in Fig. 1 indicated by the line E, which is perpendicular to the axial direction A. The radial plane E is therefore the plane which is perpendicular to the axial direction A and contains the line E.

[0066] The radial plane E is the plane in which the magnetically active core 31 of the rotor 3 is actively magnetically mounted between the end faces 271 in the stator 2 in the operating state. If the rotor 3 is not tilted and is not deflected in the axial direction A, the magnetic center plane lies in the radial plane E. The radial plane E defines the xy-plane of a Cartesian coordinate system whose z-axis runs in the axial direction A.

[0067] The radial position of the magnetically active core 31 or the rotor 3 refers to the position of the rotor 3 in the radial plane E.

[0068] Since it is sufficient for the understanding of the invention, in the drawing in the Fig. 1 Only the magnetically active core 31 of the rotor 3 is shown. It is understood that the rotor 3 can of course also comprise further components such as casings or encapsulations, which are preferably made of a plastic, or of a metal or a metal alloy, or of a ceramic or a ceramic material. Furthermore, the rotor 3 can also have blades for mixing, stirring, or pumping fluids (see, for example, Fig. 12 ) or other components.

[0069] When the rotor 3 is inserted into the cup-shaped recess 211 of the containment shell 21, the rotor 3, and in particular the magnetically active core 31 of the rotor 3, is surrounded by the radially outwardly arranged end faces 271 of the transverse limbs 27 of the coil cores 25 of the stator 2. The transverse limbs 27 thus form a plurality of salient stator poles—here, six stator poles. The transverse limbs 27 are arranged at the upper ends of the longitudinal limbs 26 and in the radial plane E. Each transverse limb 27 extends in the radial direction toward the rotor 3.

[0070] When the magnetically active core 31 of the rotor 3 is in its desired position during operation, the magnetically active core 31 is centered between the end faces 271 of the transverse limbs 27, so that the transverse limbs 27 arranged in the radial plane E are also located in the magnetic center plane. The concentrated windings 61 are arranged below the radial plane E as shown and aligned such that their coil axes extend in the axial direction A.

[0071] All first ends 261 of the longitudinal legs 26 - i.e. the ones shown ( Fig. 1 ) lower ends 261 - are connected by the return 22 (see also Fig. 3 ) are connected to each other. The return path 22 is preferably designed in a ring shape. Such designs are possible (see e.g. Fig. 1 ), in which the return path 22 extends radially inward along all first ends 261 of the longitudinal legs 26.

[0072] In order to generate the electromagnetic fields necessary for the magnetic bearing of the rotor 3 and optionally for generating a torque on the rotor 3, the longitudinal legs 26 of the coil cores 25 carry the windings designed as concentrated windings 61.

[0073] These concentrated windings 61 generate, in the operating state, those electromagnetic rotating fields with which an arbitrarily adjustable transverse force can be exerted in the radial direction on the rotor 3, so that the radial position of the rotor 3, i.e., its position in the radial plane E perpendicular to the axial direction A, can be actively controlled or regulated. Optionally, these electromagnetic rotating fields can also be used to exert a torque on the rotor 3.

[0074] The "magnetically active core 31" of the rotor 3 refers to that region of the rotor 3 which magnetically interacts with the stator 2 for generating the magnetic bearing forces and optionally for torque generation.

[0075] As already mentioned, the magnetically active core 31 is annular in this embodiment. Furthermore, the magnetically active core 31 is permanently magnetic. For this purpose, the magnetically active core 31 can comprise at least one permanent magnet, but also several permanent magnets, or—as in the embodiment described here—can be made entirely of a permanent magnetic material, so that the magnetically active core 31 is the permanent magnet. The magnetically active core 31 is, for example, magnetized in the radial direction.

[0076] Permanent magnets are typically ferromagnetic or ferrimagnetic materials that are magnetically hard, i.e., have a high coercive field strength. The coercive field strength is the magnetic field strength required to demagnetize a material. For the purposes of this application, a permanent magnet is understood to be a material with a coercive field strength, or more precisely, a coercive field strength of the magnetic polarization, of more than 10,000 A / m.

[0077] Configurations are also possible in which the magnetically active core 31 is free of permanent magnets, i.e., without permanent magnets. The rotor 3 is then configured, for example, as a reluctance rotor. The magnetically active core 31 of the rotor 3 is then made, for example, of a soft magnetic material. Suitable soft magnetic materials for the magnetically active core 31 are, for example, ferromagnetic or ferrimagnetic materials, i.e., in particular, iron, nickel-iron, cobalt-iron, silicon-iron, and mu-metal.

[0078] Furthermore, designs are possible in which the magnetically active core 31 of the rotor 3 comprises both ferromagnetic materials and permanent magnetic materials. For example, permanent magnets can be inserted or embedded into a ferromagnetic base body. Such designs are advantageous, for example, when one wants to reduce costs for large rotors by saving on permanent magnetic material.

[0079] Designs are also possible in which the rotor is designed according to the principle of a squirrel cage rotor.

[0080] Both the annular return 22 and the coil cores 25 of the stator 2 are each made of a soft magnetic material because they serve as flux guiding elements for guiding the magnetic flux.

[0081] Suitable soft magnetic materials for the coil cores 25 and the return path 22 are, for example, ferromagnetic or ferrimagnetic materials, i.e., in particular iron, nickel-iron, cobalt-iron, silicon-iron, or mu-metal. A preferred embodiment for the stator 2 is a laminated stator core, in which the coil cores 25 and the return path 22 are laminated, i.e., they consist of several thin, stacked sheet elements.

[0082] Furthermore, it is possible for the coil cores 25 and the return path 22 to consist of pressed and subsequently sintered grains of the aforementioned materials. The metallic grains are preferably embedded in a plastic matrix so that they are at least partially insulated from one another, thereby minimizing eddy current losses. Soft magnetic composite materials, which consist of electrically insulated and pressed metal particles, are therefore also suitable for the stator. In particular, these soft magnetic composite materials, also referred to as SMCs (Soft Magnetic Composites), can consist of iron powder particles coated with an electrically insulating layer. These SMCs are then formed into the desired configuration using powder metallurgy processes.

[0083] During operation of the magnetic bearing device 1, the magnetically active core 31 of the rotor 3 interacts with the stator 2 in such a way that the rotor 3 can be magnetically supported with respect to the stator 2 without contact and can preferably also be magnetically rotated without contact about the axial direction A. It is particularly advantageous that the same windings 61 with which the magnetic support of the rotor 3 is effected also serve to generate a torque on the rotor 3.

[0084] Preferably, three degrees of freedom of the rotor 3, namely its position in the radial plane E and its rotation, are then actively controllable. With regard to its axial deflection from the radial plane E in the axial direction A, the magnetically active core 31 of the rotor 3 is passively magnetically stabilized, i.e., non-controllably, by reluctance forces. With regard to the remaining two degrees of freedom, namely tilting with respect to the radial plane E perpendicular to the desired axis of rotation, the magnetically active core 31 of the rotor 3 is also passively magnetically stabilized. The rotor 3 is thus passively magnetically mounted in the axial direction A and against tilting (a total of three degrees of freedom) through the interaction of the magnetically active core 31 with the coil cores 25, or passively magnetically stabilized and actively magnetically mounted in the radial plane (two degrees of freedom).

[0085] As is generally customary, in this application, an active magnetic bearing also refers to one that is actively controllable or adjustable, for example, via the electromagnetic fields generated by the concentrated windings 61. A passive magnetic bearing or passive magnetic stabilization refers to one that is not controllable or adjustable. The passive magnetic bearing or stabilization is based, for example, on reluctance forces, which return the rotor 3 to its desired position in the event of a deflection from its desired position, for example, in the event of a displacement or deflection in the axial direction A or in the event of tilting.

[0086] In contrast to conventional magnetic bearings, the magnetic bearing device 1 – and optionally the generation of a torque acting on the rotor – is realized via electromagnetic rotating fields. For the combined generation of the magnetic bearing forces and a torque for rotating the rotor 3 about the axial direction A, it is possible, on the one hand, to use electromagnetic fields as shown in Fig 1 shown, to arrange exactly one concentrated winding 61 on each longitudinal leg 26.

[0087] On the other hand, designs are also possible in which two different winding systems are provided for the combined generation of the magnetic bearing forces and a torque for rotating the rotor 3. For this purpose, for example, exactly two concentrated windings are arranged on each longitudinal leg, which are arranged adjacent to each other with respect to the axial direction A. One of these two windings belongs to the first of the two winding systems and the other to the second of the two winding systems.

[0088] At the Fig. 1 In the embodiment shown, with exactly one concentrated winding 61 on each coil core 25, the values ​​determined in the control unit 40 for the current required for bearings and the current required for torque generation are mathematically added or superimposed—e.g., with the aid of software. The resulting total current is then impressed into the respective concentrated winding 61.

[0089] In Fig. 3 For better understanding, the return path 22 is shown separately from the coil cores 25. The return path 22 is essentially ring-shaped and extends in the assembled state (see also Fig. 1 ) radially inwardly along the first ends 261 of the longitudinal legs 26. The return path 22 is preferably laminated. In the laminated design, the return path 22 is constructed from a plurality of thin elements that are stacked parallel to one another in the axial direction A. All elements are identically designed, i.e., each essentially annular and also with the same thickness.

[0090] The back yoke 22 has a plurality of flattened portions 222 on its radially outer circumferential surface, which are planar, i.e., not curved. In the assembled state of the stator 2, a first end 261 of one of the longitudinal limbs 26, which preferably have a rectangular profile, rests against each of these flattened portions 222. The planar configuration of the flattened portions 222 ensures a large contact area between the back yoke 22 and the longitudinal limbs 26 of the coil cores 25, resulting in particularly good guidance of the magnetic flux and very low magnetic resistance at the transition between the back yoke 22 and the longitudinal limbs 26. The flattened portions can also be arranged on separate segments 225, wherein the separate segments 225 are arranged in grooves of the back yoke 22. The grooves are dimensioned so that the separate segments 225 are flush with the rest of the return path 22.

[0091] Preferably, the number of flats 222 is equal to the number of coil cores 25, so here six flats 222 are provided, which are distributed equidistantly along the outer circumference of the return path 22

[0092] Furthermore, one or more vent holes or recesses 223 can be provided on the return path 22, which extend completely through the return path 22 with respect to the axial direction A. Air can escape through the vent recesses 223, for example, when the housing 20 is filled with a thermally conductive potting compound.

[0093] In order to determine the current position of the rotor 3 in the cup-shaped recess 211, the magnetic bearing device 1 comprises a plurality - here six - magnetic field sensors 8 (see also Fig. 7 ), which, in the assembled state of the magnetic bearing device 1, are arranged around the cup-shaped recess 211. The magnetic field sensors 8 are sensors with which a magnetic field can be measured. In particular, the following sensor types are suitable as magnetic field sensors 8: Hall sensors or magnetoresistive sensors or GMR sensors (GMR: giant magnetoresistance). With the aid of the magnetic field sensors 8, the current position of the rotor 3 in the cup-shaped recess 211 of the containment shell 21 or in the radial plane E can be determined in a manner known per se.

[0094] According to a particularly preferred embodiment, which is described in Fig. 7 As shown, all magnetic field sensors 8 are arranged on a circuit board 7 and are signal-connected to it via electrical connections 81, so that all magnetic field sensors 8 can be controlled via the circuit board 7 and the signals measured by the magnetic field sensors 8 can be received and processed via the circuit board 7 or, for example, transmitted to the control device 40.

[0095] The circuit board 7 is arranged with respect to the axial direction A between the windings 61 on the one hand and the transverse legs 27 on the other hand. Fig. 7 The holding device 9, which is also shown, is designed to receive the circuit board 7. Preferably, the circuit board 7 can be fastened to the holding device 9, for example by means of a plurality of screws 75 (see Fig. 9 ).

[0096] The circuit board 7 is preferably designed as an electronics print or PCB (printed circuit board). The magnetic field sensors 8 and the electrical connections 81 are attached to the circuit board 7, for example, by means of a soldered connection. Components used for controlling the magnetic field sensors and / or for evaluating the measurement signals detected by the magnetic field sensors 8 can also be provided on the circuit board 7.

[0097] The plate 7 is essentially ring-shaped and arranged parallel to the radial plane E. As shown in Fig. 7 As can be seen, the circuit board 7 is not designed as a closed ring, but rather with a ring-segment-shaped opening 74, so that the circuit board 7 has two ends when viewed in the circumferential direction. Preferably, the circuit board 7 is arranged radially inward with respect to the longitudinal limbs 26 of the coil cores 25, specifically such that the magnetic field sensors 8 are arranged around the cup-shaped recess 211 of the can 21. Particularly preferably, the magnetic field sensors 8 are arranged equidistantly on the circuit board 7 with respect to the circumferential direction.

[0098] The circuit board 7 further comprises an electrical connection element 76, which connects the circuit board 7 to the control device 40, so that the control device 40 and the circuit board 7 can exchange electrical voltages or currents via the electrical connection element 76. The electrical connection element 76 is preferably designed as a flex circuit board. Of course, the electrical connection element 76 can also be designed differently, for example, as a cable, a cable bundle, or a ribbon cable.

[0099] As already mentioned, the magnetic bearing device 1 further comprises the holding device 9. The holding device 9 serves for a particularly simple and yet precise assembly of the magnetic bearing device 1 and a very precise positioning of the magnetic field sensors 8 relative to the cup-shaped recess 211 in which the rotor 3 is arranged in the operating state.

[0100] In the following, the holding device 9 is explained using several figures. Fig. 5 shows the holding device 9 in a perspective view, wherein the viewing direction is from the direction of the first ends 261 of the longitudinal legs 26. According to the illustration in Fig. 1 The view from below is directed towards the holding device 9. Fig. 6 shows the holding device 9 in a perspective view, with the viewing direction opposite to the viewing direction in Fig. 5 According to the presentation in Fig. 1 So the view into Fig. 6 directed from above onto the holding device 9. Both Fig. 5 as well as Fig. 6 show the holding device 9 with the circuit board 7 arranged in the holding device 9. Fig. 8 shows a sectional view of the holding device 9 with the board 7 inserted therein. For a better understanding, Fig. 9 another enlarged view of detail I from Fig. 8 .

[0101] The holding device 9 is essentially plate-shaped and annular and comprises several recesses 91 for receiving the transverse legs 27 of the coil cores 25. For each transverse leg 27, exactly one recess 91 is provided, so that the number of recesses 91 is the same as the number of coil cores 25. The holding device 9 is inserted into the can 21 (see Fig. 1 ) and extends from the bottom of the containment shell 21 in the axial direction A to a ( Fig. 1 ) lower edge, which is arranged above the windings 61 with respect to the axial direction A as shown.

[0102] The holding device 9 is designed in such a ring-shaped manner that it can be arranged around the cup-shaped recess 211 of the containment shell 21, so that the cup-shaped recess 211 is radially enclosed on the outside by the holding device 9.

[0103] The holding device 9 has an axial edge region 92 which has an outer diameter which is smaller than the diameter of the rest of the holding device 9. According to the illustration in Fig. 6 This axial edge region 92 is the upper axial edge region. The axial edge region 92 ends with respect to the axial direction A at a projection 93, at which the outer diameter of the second holding device 9 increases. The design with the axial edge region 92 of smaller diameter and the projection 93 serves to allow the containment shell 21 to enclose the holding device 9 radially on the outside. This is particularly important in Fig. 1 The containment shell 21 has a radially outer edge 212, which, in the assembled state, encompasses the axial edge region 92 of the second holding device 9. The radially outer edge 212 is designed to be so long with respect to the axial direction A that it extends at most to the projection 93.

[0104] The holding device 9 is preferably made of a plastic, and particularly preferably of a plastic that can be processed by injection molding. The holding device 9 is thus preferably designed as an injection-molded part. Suitable plastics for the production of the holding device 9 include, for example, acrylonitrile butadiene styrene (ABS), polyamide (nylon, PA), polypropylene (PP), or fiber-filled polypropylene.

[0105] The holding device 9 serves both as a holder for the circuit board 7 and as a holder for the magnetic field sensors 8, with which the magnetic field sensors 8 can be positioned very precisely relative to the cup-shaped recess 211. For this purpose, a cavity 95 is provided in the holding device 9 for each magnetic field sensor 8, which cavity is delimited with respect to the radial direction by an inner wall 951 and an outer wall 952, wherein the magnetic field sensor 8 can be inserted into the cavity 95, and wherein the cavity 95 is dimensioned such that the inner wall 951 and the outer wall 952 lie flat against the magnetic field sensor 8. This is best achieved in Fig. 9 to recognize.

[0106] An essential aspect is that both the inner wall 951 and the outer wall 952 of the cavity 95 lie flat against the magnetic field sensor 8, as this allows the position of the magnetic field sensor 8 relative to the cup-shaped recess 211 to be known with very high accuracy. The magnetic field sensors 8 are preferably rectangular. The cavity 95 is dimensioned such that the magnetic field sensor 8 can be inserted completely into the cavity 95 with respect to the axial direction A. The cavity 95 thus forms a pocket for the magnetic field sensor 8, which pocket is at least as deep with respect to the axial direction A as the extension of the magnetic field sensor 8 in the axial direction A.The width of this pocket in the radial direction, i.e. the distance measured in the radial direction between the inner wall 951 and the outer wall 952, is dimensioned such that it corresponds to the extension of the magnetic field sensor 8 in the radial direction, so that the magnetic field sensor 8 can be pushed into the cavity 95 in the axial direction and then the inner wall 951 and the outer wall 952 of the cavity 95 lie flat against the magnetic field sensor 8.

[0107] Due to this configuration, in which the magnetic field sensor 8 is enclosed on three sides by the cavity 95, on the one hand the position of the magnetic field sensor 8 is known with very high accuracy, and on the other hand the magnetic field sensor 8 arranged in the cavity 95 is also very well protected.

[0108] In order to facilitate the insertion of the magnetic field sensors 8 into the cavities 95 during assembly, it may be advantageous to design the inner wall 951 and / or the outer wall 952 slightly oblique to the axial direction, so that the cavity 95 is slightly conical when viewed in the axial direction A, wherein the cavity 95 is slightly conical with respect to the illustration in Fig. 9 tapered towards the top.

[0109] Furthermore, it is preferred that each magnetic field sensor 8 is arranged as close as possible to the cup-shaped recess 211. For this purpose, the inner diameter of the holding device 9 is dimensioned such that it is the same size as or only very slightly larger than the outer diameter DA ( Fig. 11 ) of the cup-shaped recess 211 of the containment shell 21. In the assembled state, the wall of the holding device 9, which forms the inner walls 951 of the cavities 95, rests against the cup-shaped recess 211 of the containment shell 21. Viewed in the radial direction, the inner wall 951, which delimits the cavity 95, is arranged between the cup-shaped recess 211 of the containment shell 21 and the magnetic field sensor 8.

[0110] Since the magnetic field sensors 8 are preferably arranged equidistantly with respect to the circumferential direction on the circuit board 7, the six cavities 95 for the six magnetic field sensors 8 are also preferably arranged equidistantly with respect to the circumferential direction of the holding device 9. Particularly preferably, exactly one cavity 95 is arranged between each two circumferentially adjacent recesses 91. In the assembled state, each magnetic field sensor 8 is then arranged between each two circumferentially adjacent coil cores 25.

[0111] With a view to achieving the highest possible accuracy of the position of the magnetic field sensors 8 relative to the cup-shaped recess 211, it is a preferred measure to provide a separate guide element 96 for each cavity 95, which forms the inner wall 951 or the outer wall 952 by which the cavity 95 is delimited.

[0112] In Fig. 9 an embodiment is shown in which the guide element 96 forms the outer wall 952 of the cavity 95. For a better understanding, Fig. 10 another perspective view of the separate guide element 96 from Fig. 9 . Since such a separate guide element 96 is provided for each cavity 95, there are therefore six such guide elements 96 in this embodiment. The separate guide elements 96 are separate components, i.e., components separate from the holding device 9, which are only inserted into the holding device 9 after the holding device 9 has been manufactured, in order to thus form the cavities 95 for the magnetic field sensors 8. Since the guide elements 96 are separate components, they can be manufactured with very high precision, which is advantageous for the accuracy of the position of the magnetic field sensors 8. In addition, the separate guide elements 96 make it particularly easy to adapt the dimensions of the cavity 95 to the respective magnetic field sensors 8.

[0113] How this is best done in Fig. 9 As can be seen, each separate guide element 96 has an L-shaped profile. The separate guide element 96 has a bottom 961 ( Fig. 10 ), which forms the short leg of the L, and a side wall 962, which forms the long leg of the L. The bottom 961 of the guide element 96 also forms the bottom of the cavity 95.

[0114] The side wall 962 of the guide element 96 forms the outer wall 952, which delimits the cavity 95. The side wall 962 comprises two parallel guides 963, between which the magnetic field sensor 8 is inserted when the guide element 96 is inserted into the holding device 9. The two parallel guides 963 are spaced apart by a distance D1 that corresponds to the corresponding extension of the magnetic field sensor 8, so that the magnetic field sensor 8 can be inserted between the two guides 963 and is guided by the guides 963. The two guides 963 have a length L, which, when inserted, is the extension of the guides 963 in the axial direction. The length L is dimensioned such that it is at least as large as the corresponding dimension of the magnetic field sensor 8, so that the magnetic field sensor 8 does not protrude beyond the guide element 96 with respect to the axial direction A.

[0115] As already mentioned, the holding device 9 in the embodiment described here is designed such that it can accommodate the circuit board 7 with the magnetic field sensors 8 arranged thereon. For this purpose, the holding device 9 comprises an annular edge 97 ( Fig. 9 ) with a shoulder 98 provided thereon, the shoulder 98 being arranged radially inward with respect to the edge 97. The shoulder 98 is designed and arranged such that the circuit board 7 can be placed on the shoulder 98 and rests against this shoulder 98. Optionally, the circuit board 7 can be fastened to the shoulder 98 and thus to the holding device 9 with a plurality of screws 75. Preferably, the edge 97 is designed such that it projects beyond the circuit board 7 with respect to the axial direction A. This has the advantage that the entire holding device 9 can then be cast with a potting compound and the circuit board is completely covered by the potting compound.

[0116] Fig. 11 shows a sectional view of the containment shell 21 of the stator 2 of the embodiment of the magnetic bearing device, the section being taken in the axial direction A.

[0117] The containment shell 21 with the cup-shaped recess 211 is preferably designed as a single piece. The containment shell 21 is preferably made of a plastic, and particularly preferably of a plastic that can be processed by injection molding. The containment shell 21 is thus preferably designed as an injection-molded part. Suitable plastics for the manufacture of the containment shell 21 are, for example, acrylonitrile butadiene styrene (ABS), polyamide (nylon, PA), polypropylene (PP), polytetrafluoroethylene (PTFE), perfluoroalkoxy alkanes (PFA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyimide (PI), polyetheretherketone, polysuccinimide (PSI), polyphthalamide (PPA), or polyether ether ketone (PEEK).

[0118] The containment shell 21 comprises the cup-shaped recess 211, into which the rotor 3 can be inserted, and the radially outer edge 212, which in the assembled state encompasses the axial edge region 92 of the holding device 9.

[0119] The following explains how the magnetic bearing device can be assembled very easily. Assembly can be carried out, for example, as follows: The circuit board 7 with the magnetic field sensors 8 arranged and secured thereon is inserted into the holding device 9. To do this, first insert each of the magnetic field sensors 8 into one of the cavities 95, and then the circuit board 7 is placed onto the shoulder 98 of the holding device 9. Optionally, the circuit board 7 is attached to the holding device 9 with the screws 75.

[0120] Subsequently, the holding device 9 is completely filled with a first potting compound such that the circuit board 7 is completely covered by the first potting compound. This first potting compound is preferably a soft potting compound. A soft potting compound means a potting compound that has a Shore D hardness of less than 40. Silicones or polyurethanes, for example, are suitable as the first potting compound. During operation of the magnetic bearing device 1, significant and frequent temperature fluctuations can occur, particularly in the area of ​​the holding device 9 with the magnetic field sensors 8 arranged therein. A soft potting compound is more resistant to such fluctuations. Therefore, a soft potting compound is preferred for casting the holding device 9.

[0121] The coil cores 25 are guided through the recesses 91 in the holding device 9 and through the concentrated windings 61. The magnetic return path 22 is arranged between the first ends 261 of the longitudinal legs 26. The holding device 9, the return path 22 and the coil cores 25 with the concentrated windings 61 arranged thereon are arranged in a first installation direction in the axial direction A (as shown in Fig. 2 from the left side) into the stator housing 101 of the housing 10. The electrical connecting element 76 is guided parallel to the longitudinal legs 26 of the coil cores 25 through the stator housing 101 into the control housing 102.

[0122] When the holding devices 9, the windings 61, the return path 22 and the coil cores 25 are arranged in the stator housing 101 of the housing 10, the containment shell 21 is placed on the housing 10 and connected to the housing 10 in a sealing, preferably hermetically sealed, manner, the seal 201 being arranged between the containment shell 21 and the housing 10.

[0123] Subsequently, the housing 10 of the magnetic bearing device 1 is filled with a thermally conductive potting compound. Preferably, a second potting compound is used for this purpose, which has good thermal conductivity and is different from the first potting compound. The second, thermally conductive potting compound is preferably harder than the first potting compound. The second thermal potting compound should have particularly good thermal conductivity in order to quickly and reliably dissipate the heat generated during operation into the housing, from where the heat is then dissipated primarily by convection. Suitable materials as second, thermally conductive potting compounds include polyurethanes, epoxy resins, acrylic resins, or polyesters.

[0124] After the stator housing 101 of the housing 10 has been filled with the second potting compound, the control unit 40 is inserted into the control housing 102 of the housing 10 in a second installation direction, wherein the second installation direction is opposite to the first installation direction. As shown in Fig. 2 The control unit 40 is inserted into the control housing 102 from the right. The electrical connecting element 76 is connected to the control unit 40.

[0125] When the control unit 40 is arranged in the control housing 102 of the housing 10, the housing cover 11 is placed on the housing 10 and connected to the housing 10 in a sealing, preferably hermetically sealed manner, with the sealing element 105 being arranged between the housing cover 11 and the housing 10. The housing cover 11 is secured, for example, by means of several screws 111 ( Fig. 1 ) attached to the housing 10.

[0126] Optionally, the control housing 102 of the housing 10 can also be encapsulated with a potting compound, for example, for applications with highly corrosive, aggressive, or explosive fluids. If the control housing is also encapsulated, this is done before the housing cover 11 is placed on the housing 10 and firmly connected to it.

[0127] The invention further proposes a centrifugal pump 100 for conveying a fluid, which is characterized in that the centrifugal pump 100 comprises a magnetic bearing device 1 and a rotor 3, wherein the magnetic bearing device 1 is configured according to the invention. The magnetic bearing device 1 is configured such that, in addition to the contactless magnetic bearing of the rotor 3, it can generate a torque acting on the rotor 3 that drives its rotation about the axial direction A.

[0128] Fig. 12 shows an embodiment of a centrifugal pump according to the invention, which is designated overall by the reference numeral 100, in a schematic sectional view in a section in the axial direction A. In Fig. 12 For better understanding and clarity, the housing 10 and the containment shell 21 are not shown.

[0129] The centrifugal pump 100 comprises a pump unit 50 with a pump housing 51, which includes an inlet 52 and an outlet 53 for the fluid to be pumped. The rotor 3 is arranged in the pump housing 51 and includes a plurality of vanes 54 for pumping the fluid. The pump unit 50 is designed such that the pump unit 50 can be inserted into the containment shell 21 of the stator 2 such that the magnetically active core 31 of the rotor 3 is surrounded by the end faces 271 of the transverse legs 27.

[0130] An advantageous aspect is that the rotor 3 is designed as an integral rotor because it serves as both the rotor 3 of the magnetic bearing and the rotor 3 of the centrifugal pump 100, which pumps the fluid. This design as an integral rotor offers the advantage of a very compact and space-saving design.

[0131] The stator 2 is in the housing 10 (in Fig. 12 (not shown) is arranged, which is preferably designed together with the containment shell 21 as a hermetically sealed housing 10. The control unit 40 is preferably, but not necessarily, also arranged in the housing 10. The housing 10 is preferably filled with a potting compound, for example with an epoxy resin, an acrylic resin, a polyester, or a polyurethane, so that all components arranged inside the housing 20 are surrounded by the potting compound.

[0132] The pump unit 50 is in the cup-shaped recess 211 of the containment shell 21 (in Fig. 12 not shown) so that the rotor 3 provided in the pump housing 51 is surrounded by this cup-shaped recess 211, the magnetically active core 31 of the rotor 3 being arranged between the transverse legs 27 of the coil cores 26.

[0133] The pump housing 51 is fixed to the housing 20, preferably with a plurality of screws (not shown).

[0134] The rotor 3 comprises a plurality of vanes 54 for conveying the fluid. In the exemplary embodiment described here, for example, a total of four vanes 54 are provided, this number being exemplary. The rotor 3 further comprises a casing 38, with which the magnetically active core 31 of the rotor 3 is enclosed and preferably hermetically encapsulated, so that the magnetically active core 31 of the rotor 3 does not come into contact with the fluid to be conveyed. All vanes 54 are arranged on the casing 38 and are arranged equidistantly with respect to the circumferential direction of the rotor 3. Each vane 54 extends radially outward and is connected to the casing 38 in a rotationally fixed manner. The vanes 54 can be separate components that are then fixed to the casing 38.It is of course also possible for all vanes 54 to be an integral part of the casing 38, i.e., for the casing 38 to be formed integrally with all vanes 54. The rotor 3 with the vanes 54 forms the impeller or impeller of the centrifugal pump 100, which acts on the fluid or fluids.

[0135] Depending on the application, it is preferred if the pump housing 51 of the pump unit 50 as well as the casing 38 and the vanes 54 are made of one or more plastics. Suitable plastics are: polyethylene (PE), low-density polyethylene (LDPE), ultra-low-density polyethylene (ULDPE), ethylene-vinyl acetate (EVA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP), polyurethane (PU), polyvinylidene fluoride (PVDF), acrylonitrile butadiene styrene (ABS), polyacrylic, polycarbonate (PC), polyetheretherketone (PEEK) or silicone. For many applications, the materials polytetrafluoroethylene (PTFE) and perfluoroalkoxy polymers (PFA), known under the brand name Teflon, are also suitable as plastics.

[0136] It is understood that the magnetic bearing device 1 according to the invention is also suitable for devices other than centrifugal pumps, for example for mixing devices for mixing flowable substances, for stirring devices, for example for mixing a fluid in a tank, for fans or also for devices for carrying and rotating wafers, for example in semiconductor production.

Claims

1. Magnetic bearing device for the contactless magnetic bearing of a rotor (3) comprising a disk-shaped or annular magnetically active core (31), wherein the magnetic bearing device has a stator (2) which comprises a plurality of coil cores (25), each of which comprises a longitudinal leg (26) which extends from a first end (261) in an axial direction (A) to a second end (262), and a transverse leg (27) which is arranged at the second end (262) of the longitudinal leg and extends in a radial direction which is perpendicular to the axial direction (A), wherein at least one concentrated winding (61) is provided on each longitudinal leg (26), which surrounds the respective longitudinal leg (26), wherein the stator (2) further has a cup-shaped recess (211) into which the rotor (3) can be inserted, wherein the cup-shaped recess (211) is arranged at an axial end of the stator (2),wherein the transverse legs (27) are arranged around the cup-shaped recess (211), and wherein a plurality of magnetic field sensors (8) for determining the position of the rotor (3) are arranged around the cup-shaped recess (211), , characterized in that an annular holding device (9) is provided for the magnetic field sensors (8), which has a cavity (95) for each magnetic field sensor (8) which is delimited in the radial direction by an inner wall (951) and an outer wall (952), wherein the magnetic field sensor (8) can be inserted into the cavity (95), and wherein the cavity (95) is dimensioned such that the inner wall (951) and the outer wall (952) lie flat against the magnetic field sensor (8).

2. Magnetic bearing device according to claim 1, wherein, with respect to the axial direction (A), a circuit board (7) is arranged between the windings (61) and the transverse legs (27), on which circuit board all the magnetic field sensors (8) are arranged, and wherein the holding device (9) is designed to receive the circuit board (7).

3. Magnetic bearing device according to claim 2, wherein the holding device (9) has an annular rim (97) with a shoulder (98) provided thereon, wherein the shoulder (98) is arranged radially inwardly with respect to the rim (97), and wherein the circuit board (7) bears against the shoulder (98).

4. Magnetic bearing device according to claim 3, wherein the edge (97) is designed such that it projects beyond the circuit board (7) with respect to the axial direction (A). ​5. Magnetic bearing device according to one of the preceding claims, wherein the holding device (9) has a separate recess (91) for each coil core (25), which recess surrounds the coil core (25) and receives the transverse leg (27) of the coil core (25).

6. Magnetic bearing device according to claim 5, wherein each cavity (95) is arranged between two adjacent recesses (91) with respect to the circumferential direction.

7. Magnetic bearing device according to one of the preceding claims, in which exactly six coil cores (25) are provided.

8. Magnetic bearing device according to one of the preceding claims, which comprises exactly six magnetic field sensors (8), which are preferably arranged equidistantly around the cup-shaped recess (211).

9. Magnetic bearing device according to one of claims 2-8, wherein the holding device (9) is filled with a first potting compound such that the circuit board (7) is completely covered by the potting compound.

10. Magnetic bearing device according to one of the preceding claims, wherein a separate guide element (96) is provided for each cavity (95), which forms the inner wall (951) or the outer wall (952) by which the cavity (95) is delimited.

11. Magnetic bearing device according to one of the preceding claims, wherein the stator (2) has a containment shell (21) which forms an axial end of the stator (2), wherein the containment shell (21) has the cup-shaped recess (211) into which the rotor (3) can be inserted, and wherein the containment shell (21) comprises the holding device (9) radially outwardly.

12. Magnetic bearing device according to one of the preceding claims, comprising a housing (10) comprising a stator housing (101) and a control housing (102) arranged adjacent to one another with respect to the axial direction (A), wherein the stator housing (101) is designed to accommodate the coil cores (25) with the concentrated windings (61) arranged thereon, and the control housing (102) is designed to accommodate a control unit (40) for controlling and supplying the windings (61) with electrical energy for generating electromagnetic fields. ​13. Magnetic bearing device according to claim 12, wherein the housing (10) is designed such that the coil cores (25) with the concentrated windings (61) arranged thereon can be inserted into the stator housing (101) in a first installation direction in the axial direction (A), and the control unit (40) can be inserted into the control housing (102) in a second installation direction, wherein the first installation direction is opposite to the second installation direction.

14. Magnetic bearing device according to one of the preceding claims, wherein the stator (2) is designed to generate a torque with which the rotor (3) can be magnetically driven in a contactless manner for rotation about the axial direction (A).

15. Centrifugal pump for conveying a fluid, characterized in that ​the centrifugal pump comprises a magnetic bearing device (1) according to claim 14, and a rotor (3) with a magnetically active core (31), wherein the rotor (3) can be inserted into the cup-shaped recess (211) of the containment shell (21), and wherein the rotor (3) is designed as a rotor (3) of the centrifugal pump.

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